To surely prevent dust from entering the inside of a cover and provide excellent aesthetic appearance in an air compressor.

This air compressor comprises a compressor body 5 having a motor 4 at one end of a crankcase 3 with a compressor, an air tank disposed on the compressor body, and the cover for covering the compressor body. A hole allowing a pressure gauge 90 installed on the air tank 6 side to pass therethrough is formed in the cover 7. A soft bush 93 is interposed between the hole and the pressure gauge. The bush 93 has a fitting groove 94 tightly fitted onto the inner edge of the hole of the cover and a fitting hole 95 tightly fitted onto the pressure gauge. The portion between the fitting groove 94 and the fitting hole 95 is made flexible to absorb the vibration transmitted from the compressor body.